We drove from the Bay Area to the Mt Jefferson trailhead, intending
to spend the night before climbing the next day. Somewhere along the
bumpy dirt road (which becomes serious 4WD above Jefferson Summit)
we decided we'd rather do a little after-dark walking than camp on
the cold exposed windy ridge.

We pushed Daryn's Jeep as far up the hill as it would go, stopping
at what my trailhead page shows as waypoint JEF4WD. No conventional
vehicle can go beyond here, and there's one odd spot where we crossed
a fence line and wondered if we were entering private property. There
are no signs indicating a problem, so we went as high as we could
(about 9400').

We left for the summit just after 530pm. There's a trail in places,
but mostly the route just follows the ridge north to the south summit
of Jefferson. The map shows a switchback around 10400', but we
went straight up the ridgeline because the walking was easy and the
trail was faint. Above Point 10973 the ridgeline becomes very rocky,
and the trail on the west side of the ridge becomes much more clear,
so we traversed on the trail between 11200-11400', then scrambled
sharply up onto the summit ridge for the rest of the climb.

Arriving on top at 745pm, we were just in time for sunset. That's
when it got REALLY cold! Here we were in the desert on August, and
my hands were going numb in thin gloves. The wind was howling and
it was now dark, but we both had headlamps and the route was obvious.

We were back to the car at 930pm, frozen and windblown but glad we
didn't have to camp near Jefferson Summit. We camped at 8400'
(waypoint JEFCMP in the trailhead page), on a dirt side road,
where the summit wind didn't bother us.

The next morning we slept in (until sunrise, which is sleeping in for us).
We bounced down the road to Belmont, through Manhattan, south of Rainier,
and up the Reese River toward Arc Dome. This shortcut between the two
peaks (documented on the trailhead page) saved a lot of time vs. going
down to Hwy 6 or up to Hwy 50. We got to the Columbine Campground
(the Arc Dome trailhead, waypoint ARCDTH on the trailhead page)
at 10am under completely cloudy skies, packed up, and headed for the
peak right away. The weather looked bad but it never dumped on us.

Arc Dome from the ridge:

Near the trailhead there is a trail junction sign that says two trails
go left (waypoint PACKT1 where the map shows the pack trail in purple),
but the main trail goes straight and that direction isn't labelled!
Around 9200' (waypoint ROUTEB) is where I think the DPS Guide's Route B
takes off up a side canyon (blue on my map). We stayed on the trail
because the side canyon looked brushy (and because Dayrn likes trails).

Over the shoulder and into the next canyon, there were grazing cattle
behind a fence. Or maybe ABOVE the fence! Either way, the trail skirts
the fenced area on the up-canyon side (where we briefly lost it), then
crosses a stream where it turns sharply west and climbs onto a ridge.
This ridge is the DPS Guide's Route A, and I believe the point where
the trail turns and crosses a stream (waypoint ROUTEC) is where
Route C goes up the canyon (green on my map). The trail we followed
(red on my map) doesn't match the trail on the map (highlighted in
yellow) for a ways, but joins up near Point 9986.

The trail leaves the ridge and sidehills to a trail junction
(waypoint ROUTEA) before switchbacking up onto the main ridge. At
waypoint PACKT2 the map shows the pack trail joining the trail we
were on. We saw a cairn but no sign of the pack trail! It's an
easy ridge walk south from here toward the peak. On the way in we
lost the faint use trail and drifted a bit too far west forcing
us to traverse back to the higher of two saddles (where we picked
up a good trail again). Stay well west of Point 11406, but then
drift east (left) so you stay on the ridge line and pick up the
trail at the 11040' saddle I've labelled 11KSAD.

From here to the peak is a good trail. It's disheartening to climb
to 11.3k before dropping to 10.7k, but there's really no alternative.
From this saddle (waypoint ARCSAD) to Arc Dome (waypoint ARCDOM) is
a 1000' grunt on switchbacks that seem endless. In our case, the
wind was so cold we were wearing winter hats, goretex, and wishing
for warmer gloves. I wore a down coat on the way down (in AUGUST)
and we even had a few snow flurries.

We got to the top just before 230pm, and retraced our path back
to the car well before dark for a calm night out of the wind.
With the climb on both sides of the big saddle, this is a 14 mile
day with 4400' of gain and loss.